1. Field of the Invention
This invention relates to a suspension for a motor vehicle.
2. Description of the Prior Art
As disclosed in U.S. Pat. No. 4,269,432, there has been known an automotive suspension system which is arranged to cause rear wheels to toe in or to straighten the rear wheels when the side force acting on the rear wheels is relatively small in order to improve running stability during straight travel of the vehicle.
In the case of a front-engine-front-drive car, when a large side force acts on the rear wheels such as during sharp cornering, the grip of the driving wheels or the front wheels is weakened and understeer tendency is enhanced, thereby adversely affecting the steering performance.
Accordingly when the automotive suspension system disclosed in the aforesaid U.S. patent is directly applied to the front-engine-front-drive car in order to improve running stability during straight travel, the understeer tendency is further enhanced as the side force acting on the rear wheels increases and the steering performance of the vehicle tends to be unsatisfactory.
On the other hand, when the suspension system is arranged so that the rear wheels are caused to toe out when a large side force acts thereon in order to weaken understeer tendency, thereby improving the steering performance, the running stability during straight travel of the vehicle is adversely affected since the rear wheels tend to substantially toe out even when the side force acting on the rear wheels is relatively small.
In the case of a front-engine-rear-drive car, when a large side force acts thereon, the grip of the driving wheels or rear wheels is weakened, and the understeer tendency is extremely weakened, producing oversteer tendency, whereby the vehicle tends to make a sharp turn inwardly, that is, so-called reverse-steer occurs.
In the front-engine-rear-drive car, by enlarging the toe-in of the rear wheels, the reverse-steer can be prevented or suppressed when a large side force acts thereon. However, this approach is disadvantageous in that the understeer tendency is excessively enhanced when the side force acting on the vehicle is relatively small and the steering performance is significantly lowered.